Table 1. Clinical observer study of CT temporal subtraction system for the detection of lung nodule and bone metastasis.

	Authors	Dimension of CT-TS	CT data images (dose, slice thickness)	Data sets	Readers	Observer study	Analysis	Diagnostic ability (average)	Published year
Lung	Abe et al.	2D	low dose, 10 mm slice thickness	30: 14 cases with primary lung cancer (5–24 mm) and 16 control cases	7: 4 attendings and 3 residents	Without TS vs. With TS	ROC	Az: 0.868 vs. 0.930 (P=0.007)	2004
	Aoki et al.	3D	standard dose, 2 mm slice thickness	50: 25 cases with non-calcificated nodules (30 lesions, 5–19 mm) and 25 control cases	8: 4 attendings and 4 residents	Without TS vs. With TS	JAFROC	FOM: 0.838 vs. 0.894 (P=0.033)	2014
	Terasawa et al.	3D	standard dose, 2 mm slice thickness	50: 25 cases with ground-glass nodules diagnosed lung cancer (31 lesions, 5–22 mm) and 25 control cases	8: 4 attendings and 4 residents	Without TS vs. With TS	JAFROC	FOM: 0.861 vs. 0.912 (P<0.001)	2017
Bone	Sakamoto et al.	3D*	No description of slice thickness Whole body bone*	60*: 30 cases with bone metastases (65 lesions)* and 30 control cases*	7: 7 radiologists (6–28 years’ experience)	Without TS vs. With TS	JAFROC	FOM: 0.758 vs. 0.835 (P=0.092)	2017
	Iwano et al.	3D	0.6 or 1 mm slice thickness Spine	30 cases with bone metastases (46 lesions)	2 residents (2.5 years’ experience)	Without TS vs. With TS	ROC	AUC: Reader A; 0.849 vs. 0.902 (P=0.021) Reader B; 0.889 vs. 0.910 (P=0.341)	2017
	Ueno et al.	3D	1 mm slice thickness Spine	40: 20 cases with bone metastases (135 lesions) and 20 control cases	8: 4 attendings and 4 residents	Without TS vs. With TS	JAFROC	FOM: 0.856 vs. 0.884 (P=0.037)	2018
	Hoshiai et al.	3D	2 mm slice thickness Spine	40: 20 cases with bone metastases (56 lesions) and 20 control cases	10: 5 attendings and 5 residents	Without TS vs. With TS	FROC	FOM: Experienced radiologists; 0.898 vs. 0.892 (P=0.852) Residents; 0.849 vs. 0.902 (P=0.083)	2019
	Onoue et al.	3D*	No description of slice thickness Whole body bone *	60: 30 cases with bone metastases (65 lesions)* and 30 control cases*	4 residents	Without TS vs. With TS	JAFROC	FOM: 0.657 vs. 0.796 (P<0.0001)	2019
	Onoue et al.	3D	1 mm slice thickness Whole body bone	60: 30 cases with bone metastases (78 lesions) and 30 control cases	12 radiologists (6–25 years’ experience)	NM-Pair (CTs with Bone scintigraphy) vs. TS-Pair (CTs with TS)	JAFROC	FOM: 0.691 vs. 0.742 (P=0.070)	2019

*, Same data sets and TS images. CT, computed tomography; TS, temporal subtraction; ROC, receiver operating characteristic; JAFROC, jackknife free-response receiver operating characteristic; FROC, free-response receiver operating characteristic; FOM, figure of merit; AUC, area under the ROC curve; Az, the binormal model estimate of the true area AUC under the ROC curve.